Navigating Dependency Injection with Metro

GDG Devfest Incheon 2025에서 진행한 Metro로 KMP에서 의존성 주입 사용하기의 Speaker Deck입니다.
Thanks for Zac Sweers :)

Transcript

1. Metro۽ KMPীࢲ ੄ઓࢿ ઱ੑ ࢎਊೞӝ HyunWoo Lee
2. Navigating Dependency Injection with Metro HyunWoo Lee X Zac Sweers
3. https://speakerdeck.com/l2hyuwnoo/navigating- dependency-injection-with-metro Viva Republica Android/React Native Engineer Community & Open Source Lover - GDG Korea Android, Kotlin User Groups Seoul - Contributer & Maintainer Making a new frontier of React Native X Android Granite ❤ Apps In Toss ❤
4. Dependency Injection (੄ઓࢿ ઱ੑ)
5. ੄ઓࢿ ઱ੑ੉ۆ?
6. ੄ઓࢿ ઱ੑ੉ۆ? class WeatherApp { fun run(location: String) { val service = WeatherService() } }
7. ੄ઓࢿ ઱ੑ੉ۆ? class WeatherApp { fun run(location: String) { val service = WeatherService() val formatter = WeatherFormatter() } }
8. ੄ઓࢿ ઱ੑ੉ۆ? class WeatherApp { fun run(location: String) { val service = WeatherService() val formatter = WeatherFormatter() val forecast = service.getForecast(location) println(formatter.format(forecast)) } }
9. ੄ઓࢿ ઱ੑ੉ۆ? class WeatherApp { fun run(location: String) { val service = WeatherService() val formatter = WeatherFormatter() / / . . . } }
10. ੄ઓࢿ ઱ੑ੉ۆ? class WeatherApp { private val service = WeatherService() private val formatter = WeatherFormatter() fun run(location: String) { / / . . . } }
11. ੄ઓࢿ ઱ੑ੉ۆ? class WeatherApp { private val service =aWeatherService() private val formatter = WeatherFormatter() fun run(location: String) { / / . . . } } ࢲ਎ 🌸 24° ب௡ 🇯🇵 25° ׏਄ 🗽 31°
12. Singletons class WeatherApp { private val service = WeatherService.getInstance() }
13. Singletons class WeatherApp { private var service = WeatherService.getInstance() inner class Backdoor { fun setService(service: WeatherService) = // ... } }
14. Service Locator class WeatherApp { private val service: WeatherService = getApplication().getWeatherService() }
15. Service Locator class WeatherApp { private val service: WeatherService by injector.instance() }
16. Service Locator class WeatherApp { private val service: WeatherService by inject() }
17. Service Locator class WeatherApp { private val service: WeatherService by inject() } @Test fun exampleTest() { startKoin { modules( module { single { WeatherService() } }) } / / … }
18. class WeatherApp { private val service: WeatherService = / /. .. }
19. class WeatherApp( private val service: WeatherService )
20. "Don't call us, we'll call you" —The Hollywood Principle
21. ࣻز ઱ੑ class WeatherApp( private val service: WeatherService )
22. ࣻز ઱ੑ class WeatherApp( private val service: WeatherService ) @Test fun exampleTest() { val app = WeatherApp(WeatherService()) / / . . . }
23. ࣻز ઱ੑ class WeatherApp( private val service: WeatherService ) @Test fun exampleTest() { val app = WeatherApp(FakeWeatherService()) / / . . . }
24. ࣻز ઱ੑ class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter ) { / / . . . } fun main() { val service = WeatherService() val formatter = WeatherFormatter() val app = WeatherApp(service, formatter) }
25. ࣻز ઱ੑ class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter ) { / / . . . } fun main() { val httpClient = HttpClient() val service = WeatherService(httpClient) val formatter = WeatherFormatter() val app = WeatherApp(service, app) }
26. ࣻز ઱ੑ class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter ) { / / . . . } fun main() { val cache = Cache() val httpClient = HttpClient(cache) val service = WeatherService(httpClient) val formatter = WeatherFormatter() val app = WeatherApp(service, app) }
27. class Cache(…) class HttpClient(private val cache: Cache) class WeatherService(private val httpClient: HttpClient) class WeatherFormatter(…) class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter ) fun main() { val cache = Cache() val httpClient = HttpClient(cache) val service = WeatherService(httpClient) val formatter = WeatherFormatter() val app = WeatherApp(service, app) } ࣻز ઱ੑ
28. Metroܳ ࣗѐ೤פ׮
29. ৵ Metroܳ ࣑݅٘աਃ? Dagger-style code gen Kotlin- fi rst Anvil aggrega ti on Mul ti pla tf orm Compiler plugin IDE diagnos ti cs* Metro
30. ৵ Metroܳ ࣑݅٘աਃ? Dagger-style code gen Kotlin- fi rst Anvil aggrega ti on Mul ti pla tf orm Compiler plugin IDE diagnos ti cs* Metro moshix, RCP Circuit, RCP anvil-ksp compose-lints anvil
31. Getting Star t ed plugins { id("dev.zacsweers.metro") version "0.6.6" }
32. Metro DI Constructor/assisted/member/function injection Providers Multibindings Scopes Runtime intrinsics
33. Metro DI class Cache(…) class HttpClient(private val cache: Cache) class WeatherService(private val httpClient: HttpClient) class WeatherFormatter(…) class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter )
34. Metro DI @Inject class Cache(…) @Inject class HttpClient(private val cache: Cache) @Inject class WeatherService(private val httpClient: HttpClient) @Inject class WeatherFormatter(…) @Inject class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter )
35. Metro DI fun main() { val cache = Cache() val httpClient = HttpClient() val service = WeatherService(httpClient) val formatter = WeatherFormatter() val app = WeatherApp(service, formatter) }
36. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp } fun main() { val app = createGraph<AppGraph>().app }
37. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp }
38. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp }
39. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp } class HttpClient class WeatherFormatter class Cache class WeatherService
40. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp } @Component interface AppGraph { val app: WeatherApp }
41. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp } fun main() { val app = createGraph<AppGraph>().app }
42. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp } fun main() { val app = createGraph<AppGraph>().app }
43. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp } fun main() { val app = AppGraph.$$MetroGraph().app }
44. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp } fun main() { val app = createGraph<AppGraph>().app }
45. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @DependencyGraph.Factory interface Factory { fun create(@Provides useMetric: Boolean) : AppGraph } } fun main() { val app = createGraph<AppGraph>().app }
46. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @DependencyGraph.Factory interface Factory { fun create(@Provides useMetric: Boolean) : AppGraph } } fun main() { val app = createGraph<AppGraph>().app }
47. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @DependencyGraph.Factory interface Factory { fun create(@Provides useMetric: Boolean) : AppGraph } } fun main() { val app = createGraphFactory<AppGraph.Factory>() .create(useMetric = true) .app }
48. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp }
49. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @Provides fun provideCache() : Cache = Cache() }
50. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @Provides fun provideCache(fs: FileSystem) : Cache = Cache(fs) }
51. Metro DI @DependencyGraph interface AppGraph : CacheProviders { val app: WeatherApp } interface CacheProviders { @Provides fun provideCache(fs: FileSystem) : Cache = Cache(fs) }
52. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @Provides fun provideCache() : Cache = Cache() }
53. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @Provides fun provideCache() : Cache = Cache() @Provides fun provideFormatterCache() : Cache = Cache() }
54. Metro DI @Qualif i er
55. Metro DI @Qualif i er annotation class Named(val value: String)
56. Metro DI @DependencyGraph interface AppGraph { val app: WeatherApp @Provides fun provideCache() : Cache = Cache() @Named("FormatterCache") @Provides fun provideFormatterCache() : Cache = Cache() }
57. Metro DI @Named("FormatterCache") Cache
58. Metro DI @Named("FormatterCache") Cache Type
59. Metro DI @Named("FormatterCache") Cache Type Quali fi er
60. Metro DI @Named("FormatterCache") Cache TypeKey
61. What's a Binding?
62. What's a Binding? @Provides fun provideCache() : Cache = Cache()
63. Injection class HttpClient(private val cache: Cache)
64. Injection @Inject class HttpClient(private val cache: Cache)
65. Injection class HttpClient( private val cache: Cache, private val timeout: Duration, ) { @Inject constructor(cache: Cache) : this(cache, 30.seconds) }
66. Metro DI @Inject class Cache @Inject class HttpClient( private val cache: Cache ) @Inject class WeatherService( private val httpClient: HttpClient ) @Inject class WeatherFormatter @Inject class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter ) @DependencyGraph interface AppGraph { val app: WeatherApp } fun main() { val app = createGraph<AppGraph>().app }
67. Scoping @Scope
68. Scoping @Scope annotation class SingleIn(val scope: KClass <*> )
69. Scoping @SingleIn(AppScope : : class)
70. Scoping @DependencyGraph interface AppGraph { val app: WeatherApp } @SingleIn(AppScope : : class)
71. Scoping @SingleIn(AppScope : : class) @DependencyGraph interface AppGraph { val app: WeatherApp }
72. Scoping @SingleIn(AppScope : : class) @Singleton
73. Scoping @SingleIn(AppScope : : class) @DependencyGraph interface AppGraph { val app: WeatherApp }
74. Scoping @Inject class WeatherService( private val httpClient: HttpClient )
75. Scoping @Inject @SingleIn(AppScope : : class) class WeatherService( private val httpClient: HttpClient )
76. Scoping @SingleIn(AppScope : : class) @Inject class WeatherService( private val httpClient: HttpClient ) @Inject class WeatherApp( private val service: WeatherService private val formatter: WeatherFormatter ) @DependencyGraph interface AppGraph { val app: WeatherApp } Always same instance
77. Scoping ӝࠄ੸ਵ۽ ݽٚ bindingҗ Ӓې೐ח scope ૑੿੉ উغয੓਺ Scope੉ ૑੿ػ ߄ੋ٬ٜী ೠ೧ࢲ double-checked lockingਵ۽ ૑ো ୡӝച Scope਷ bindingਸ ੿੄ೞח ଃীࢲ ࢶ঱, ੉ܳ ࢎਊೞח ଃীࢲ scopeਸ ঌ ೙ਃח হ਺ ౠ੿ binding type਷ scope ૑੿ ࠛо
78. More Bindings
79. @Binds
80. @Binds interface Bindings { @Binds fun bind(int: Int) : Number @Binds val String.bind: CharSequence }
81. @Binds @Binds fun bind(int: Int) : Number @Inject class HttpClient(timeoutMillis: Number)
82. @Binds @Binds fun bind(int: Int) : Number @Inject class HttpClient(timeoutMillis: Number)
83. @Binds @Binds fun bind(int: Int) : Number @Inject class HttpClient(timeoutMillis: Number)
84. @Binds Binding impl types as interfaces they implement @Binds val Int.bind: Number
85. @Binds Binding impl types as interfaces they implement Binding types into multibindings @Binds val Int.bind: Number @Binds @IntoSet val Int.bind: Number
86. @Binds Binding impl types as interfaces they implement Binding types into multibindings Binding types as nullable variants @Binds val Int.bind: Number @Binds @IntoSet val Int.bind: Number @Binds val Int.bind: Int?
87. @Binds Binding impl types as interfaces they implement Binding types into multibindings Binding types as nullable variants Binding types with different quali fi ers @Binds val Int.bind: Number @Binds @IntoSet val Int.bind: Number @Binds val Int.bind: Int? @Binds @Named("timeout") val Int.bind: Int
88. Assisted Injection
89. Assisted Injection @Inject class UserRepository( val id: String, val httpClient: HttpClient, val db: UserDb )
90. Assisted Injection @Inject class UserRepository( @Assisted val id: String, val httpClient: HttpClient, val db: UserDb )
91. Assisted Injection @Inject class UserRepository( @Assisted val id: String, val httpClient: HttpClient, val db: UserDb ) { @AssistedFactory interface Factory { fun create(id: String) : UserRepository } }
92. Assisted Injection @Inject class UserRepository( @Assisted val id: String, val httpClient: HttpClient, val db: UserDb ) { @AssistedFactory interface Factory { fun create(id: String) : UserRepository } }
93. Assisted Injection @Inject class WeatherApp( val factory: UserRepository.Factory ) { fun run() { val userRepo = factory.create("d3938c4891ae") } } @Inject class UserRepository( @Assisted val id: String, val httpClient: HttpClient, val db: UserDb ) { @AssistedFactory interface Factory { fun create(id: String) : UserRepository } }
94. Multibindings @DependencyGraph interface AppGraph { }
95. Multibindings @DependencyGraph interface AppGraph { val interceptors: Set<Interceptor> val eventHandlers: Map<String, EventHandler> }
96. Multibindings @DependencyGraph interface AppGraph { val interceptors: Set<Interceptor> val eventHandlers: Map<String, EventHandler> @Provide @IntoSet fun provideLoggingInterceptor() : Interceptor = LoggingInterceptor() }
97. Multibindings @DependencyGraph interface AppGraph { val interceptors: Set<Interceptor> val eventHandlers: Map<String, EventHandler> @Provide @IntoSet fun provideLoggingInterceptor() : Interceptor = LoggingInterceptor() } @Inject @IntoMap @StringKey("ping") class PingHandler : EventHandler
98. Multibindings @DependencyGraph interface AppGraph { @Multibinds val interceptors: Set<Interceptor> @Multibinds val eventHandlers: Map<String, EventHandler> }
99. Multibindings @DependencyGraph interface AppGraph { @Multibinds(allowEmpty = true) val interceptors: Set<Interceptor> @Multibinds(allowEmpty = true) val eventHandlers: Map<String, EventHandler> }
100. @MapKey Multibindings
101. @MapKey annotation class ClassKey(val value: KClass <*> ) Multibindings
102. @MapKey annotation class StringKey(val value: String) Multibindings
103. @Inject @IntoMap @StringKey("ping") class PingHandler : EventHandler Multibindings
104. @Provides @ElementsIntoSet fun provideInterceptors() : Set<Interceptor> = setOf(…) Multibindings
105. Aggregation
106. Aggregation @DependencyGraph interface AppGraph
107. Aggregation @DependencyGraph(scope = AppScope : : class) interface AppGraph
108. Aggregation @DependencyGraph(scope = AppScope : : class) interface AppGraph @SingleIn(scope = AppScope : : class)
109. Aggregation @DependencyGraph(AppScope : : class) / / @SingleIn(AppScope : : class) / / Implicit! interface AppGraph
110. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache }
111. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache } @Inject class CacheImpl(…) : Cache
112. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache } @Inject class CacheImpl(…) : Cache
113. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache @Binds val CacheImpl.bind: Cache } @Inject class CacheImpl(…) : Cache
114. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache } @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache
115. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph : CacheImpl.AppScope$$Contribution { val cache: Cache } @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache { @MetroContribution interface AppScope$$Contribution { @Binds val CacheImpl.bind: Cache } }
116. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache } @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache
117. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache } @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache, Closeable
118. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache } @ContributesBinding(AppScope : : class, binding = binding<Cache>()) @Inject class CacheImpl(…) : Cache, Closeable
119. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache<Forecast> } @ContributesBinding(AppScope : : class, binding = binding<Cache<Forecast > > ()) @Inject class CacheImpl(…) : Cache<Forecast>, Closeable
120. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache } @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache
121. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val interceptors: Set<Interceptor> } @ContributesIntoSet(AppScope : : class) @Inject class LogcatInterceptor(…) : Interceptor
122. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph { val eventHandlers: Map<String, EventHandler> } @Inject @ContributesIntoMap(AppScope : : class) @StringKey("ping") class PingHandler : EventHandler
123. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph @ContributesTo(AppScope : : class) interface Accessors { val eventHandlers: Map<String, EventHandler> }
124. What's a Contribution? @DependencyGraph(AppScope : : class) interface AppGraph : Accessors @ContributesTo(AppScope : : class) interface Accessors { val eventHandlers: Map<String, EventHandler> }
125. @DependencyGraph(AppScope : : class) interface AppGraph { val cache: Cache val interceptors: Set<Interceptor> val eventHandlers: Map<String, EventHandler> } @ContributesIntoSet(AppScope : : class) @Inject class LogcatInterceptor(…) : Interceptor @Inject @ContributesIntoMap(AppScope : : class) @StringKey("ping") class PingHandler : EventHandler @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache :lib - network :app :lib - events :lib - cache
126. Intrinsics
127. Intrinsics Provider Lazy @Inject class HttpClient(val cache: Cache) { init { val cacheInstance = cache } }
128. Intrinsics Provider Lazy @Inject class HttpClient(val cache: Provider<Cache>) { init { val cacheInstance = cache() } }
129. Intrinsics Provider Lazy @Inject class HttpClient(val cache: Lazy<Cache>) { init { val cacheInstance = cache.value } }
130. Graph Extensions
131. Graph Extensions @GraphExtension interface LoggedInGraph { val user: User }
132. Graph Extensions @GraphExtension interface LoggedInGraph { val user: User } @DependencyGraph interface AppGraph { val loggedInGraph: LoggedInGraph }
133. Graph Extensions Factories that you can declare instead @GraphExtension interface LoggedInGraph { val user: User } @DependencyGraph interface AppGraph { val loggedInGraph: LoggedInGraph }
134. Graph Extensions Factories that you can declare instead @GraphExtension interface LoggedInGraph { val user: User @GraphExtension.Factory interface Factory { fun create(@Provides id: String) : LoggedInGraph } } @DependencyGraph interface AppGraph { val loggedInGraphFactory: LoggedInGraph.Factory }
135. Graph Extensions Factories that you can declare instead @GraphExtension interface LoggedInGraph { val user: User @GraphExtension.Factory interface Factory { fun createLoggedInGraph() : LoggedInGraph } } @DependencyGraph interface AppGraph : LoggedInGraph.Factory / / usage val loggedInGraph = appGraph.createLoggedInGraph()
136. Graph Extensions Factories that you can declare instead Scope annotations @GraphExtension @SingleIn(LoggedInScope : : class) interface LoggedInGraph { val user: User }
137. Graph Extensions Factories that you can declare instead Scope annotations Aggregation scopes @GraphExtension(LoggedInScope : : class) interface LoggedInGraph { val user: User }
138. Graph Extensions Factories that you can declare instead Scope annotations Aggregation scopes Provider/Binds callables @GraphExtension(LoggedInScope : : class) interface LoggedInGraph { val user: User @Provides fun provideUser() : User = … }
139. Graph Extensions Factories that you can declare instead Scope annotations Aggregation scopes Provider/Binds callables Their own extensions! @GraphExtension interface LoggedInActivityGraph { val user: User val activity: Activity } @GraphExtension interface LoggedInGraph { val user: User val loggedInActivityGraph: LoggedInActivityGraph } @DependencyGraph interface AppGraph { val loggedInGraph: LoggedInGraph }
140. Metroח যڌѱ ز੘ೡө? @DependencyGraph interface AppGraph { val app: WeatherApp }
141. о੢ рױೠ Gradle ౵੉೐ۄੋ @DependencyGraph interface AppGraph { val app: WeatherApp } kotlinc (Frontend and Backend) compileKotlin .class f i les
142. ݣ౭೒ۖಬীࢲח? @DependencyGraph interface AppGraph { val app: WeatherApp } kotlinc (Frontend and Backend) compileKotlin .class .js .wasm . . .
143. KSP ࠽٘ ౵੉೐ۄੋ @DependencyGraph interface AppGraph { val app: WeatherApp } <compiled binaries> kotlinc (Frontend only) KSP source f i les kotlinc (Frontend and Backend) compileKotlin
144. kotlinc (Frontend only) Stub gen .java f i les Kapt (javac) Kapt source f i les kotlinc (Frontend and Backend) compileKotlin .class f i les KAPTܳ ࢎਊೠ׮ݶ?
145. kotlinc (Frontend only) Stub gen .java f i les Kapt (javac) Kapt source f i les kotlinc (Frontend and Backend) compileKotlin .class f i les javac compileJava More .class f i les KAPTܳ ࢎਊೠ׮ݶ?
146. kotlinc (Frontend only) Stub gen .java f i les Kapt (javac) Kapt source f i les kotlinc (Frontend and Backend) compileKotlin .class f i les javac compileJava More .class f i les HILT ࠽٘ ౵੉೐ۄੋ javac :hiltJavaCompileDebug Even more .class f i les
147. kotlinc (Frontend only) Stub gen .java f i les Kapt (javac) Kapt source f i les kotlinc (Frontend and Backend) compileKotlin .class f i les javac compileJava More .class f i les HILT ࠽٘ ౵੉೐ۄੋ javac :hiltJavaCompileDebug Even more .class f i les
149. Metro Build Pipeline @DependencyGraph interface AppGraph { val app: WeatherApp } kotlinc (Frontend and Backend) compileKotlin binary f i les
150. Metro Build Pipeline
151. https://zacsweers.github.io/metro/latest/ per f ormance.html Metro KIA Anvil-KSP Anvil-KAPT
152. Metro Build Pipeline @DependencyGraph interface AppGraph { val app: WeatherApp } kotlinc (Frontend and Backend) compileKotlin binary f i les
153. Metro Build Pipeline binary f i les Frontend Backend Source f i les
154. Metro Build Pipeline binary f i les Frontend Backend FIR IR Lowering Parse/PSI Source f i les
155. Metro Build Pipeline binary f i les Frontend Backend FIR IR Lowering Parse/PSI f i r2ir Source f i les
156. Frontend ࣗझ ౵य ૓ױ(diagnostics) ࠁҊ ஹ౵ੌ ળ࠺о ػ Frontend IR ( FIR) ౟ܻܳ ࠽٘
157. Frontend Source f i les
158. Frontend Parse/PSI Source f i les
159. Frontend FIR Parse/PSI Source f i les
160. Frontend FIR
161. Frontend FIR AnalysisHandlerExtension
162. Frontend FIR
163. Frontend FIR Declaration ࢤࢿ Super t ype ࢤࢿ ࢚క ߸ജ
164. Declaration ࢤࢿ Constructor-injected classes/providers @Inject class Cache { / / Generated by Metro class $$MetroFactory : Factory<Cache> { constructor() companion object { fun create() : $$MetroFactory fun newInstance() : Cache } } }
165. Declaration ࢤࢿ Constructor-injected classes/providers Assisted factory impls @AssistedFactory interface Factory { fun create(id: String) : UserRepository / / Generated by Metro class $$Impl : Factory }
166. Declaration ࢤࢿ Constructor-injected classes/providers Assisted factory impls Contribution interfaces @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache { / / Generated by Metro @MetroContribution interface AppScope$$Contribution }
167. Declaration ࢤࢿ Constructor-injected classes/providers Assisted factory impls Contribution interfaces Etc
168. Declaration ࢤࢿ @DependencyGraph.Factory interface Factory { fun create() : AppGraph / / Generated in FIR class $$Impl : Factory { constructor() } }
169. Declaration ࢤࢿ @DependencyGraph.Factory interface Factory { fun create() : AppGraph / / Generated in FIR class $$Impl : Factory { constructor() } } @DependencyGraph.Factory interface Factory { fun create() : AppGraph class $$Impl : Factory { constructor() { } / / Implemented in IR override fun create() : AppGraph = AppGraph.$$MetroGraph() } }
170. Super t ype ࢤࢿ
171. Super t ype ࢤࢿ @DependencyGraph(AppScope : : class) interface AppGraph
172. Super t ype ࢤࢿ @DependencyGraph(AppScope : : class) interface AppGraph @ContributesBinding(AppScope : : class) @Inject class CacheImpl(…) : Cache { / / Generated by Metro @MetroContribution interface AppScope$$Contribution } @ContributesTo(AppScope : : class) interface NetworkProviders { / / . . . }
173. ࢚క ߸ജ
174. Status Transformers
175. ࢚క߸ജ FirProvidesStatusTransformer FirAccessorOverrideStatusTransformer (Metro 0.6.6+)
176. Frontend FIR
177. Frontend FIR Checkers
178. Checkers ױ ೞա੄ ୶࢚ ೣࣻ݅ оઉঠ ೞח૑ ೣࣻо dependency graphܳ ߈ജೞח૑ ਬബೠ ഋక੄ ಁ۞޷ఠܳ о૑Ҋ ੓ח૑ …੉৻ীب 100ѐ ؊ object DependencyGraphCreatorChecker
179. Checkers
180. Metro Build Pipeline binary f i les Frontend Backend FIR IR Lowering Parse/PSI f i r2ir Source f i les
181. IR ߸ജ
182. IR ߸ജ 1. FIRױীࢲ ࢤࢿೠ Binds ೣٜࣻਸ पઁ۽ ҳഅೞӝ 2. Ӓ ৻ী աݠ૑ ݽٚ Ѫٜী ؀ೠ ߸ജ ੘স
183. Metro IR Pipeline 1. Ӓې೐о ইצ ௿ېझٜਸ ݢ੷ ߸ജ 2. ੄ઓࢿ Ӓې೐ܳ ߸ജ A. Ӓې೐ ҳࢿ ؘ੉ఠ(߄ੋ٬, ܖ౟, GraphExtension) ࣻ૘ B. GraphExtension ୊ܻ C. BindingGraph ࢤࢿ D. ਬബࢿ Ѩࢎ E. IR Ӓې೐ ҳഅ • ߄ੋ٬ٜ ଻ਕ֍ӝ • Tarjan validation(ъೠਃࣗ Ѿ೤ Ѩ ࢎ) + Kahn sorting(ਤ࢚੿۳) • Ѿҗ ߈ജ • ੿۳ػ(top sorted) • ب׳ оמೠ(reachable) • ૑ো୊ܻ೧ঠ ೡ(deferred) ఃٜ
184. @Inject @SingleIn(AppScope : : class) class WeatherService( httpClient: HttpClient ) @Inject class WeatherFormatter(…) @Inject class WeatherApp( service: WeatherService formatter: WeatherFormatter ) @DependencyGraph @SingleIn(AppScope : : class) interface AppGraph { val app: WeatherApp @Provides fun provideCache() : Cache = Cache() @Provides fun provideHttpClient(cache: Cache) : HttpClient = HttpClient(cache) } Metro IR Pipeline
185. Metro IR Pipeline @DependencyGraph @SingleIn(AppScope : : class) interface AppGraph { val app: WeatherApp @Provides fun provideCache() : Cache = Cache() @Provides fun provideHttpClient(cache: Cache) : HttpClient = HttpClient(cache) }
186. Metro IR Pipeline Scope — @SingleIn(AppScope : : class) @DependencyGraph interface AppGraph { val app: WeatherApp @Provides fun provideCache() : Cache = Cache() @Provides fun provideHttpClient( cache: Cache ) : HttpClient = HttpClient(cache) }
187. Metro IR Pipeline Scope — @SingleIn(AppScope : : class) IrBinding.Provided — Cache @DependencyGraph interface AppGraph { val app: WeatherApp @Provides fun provideHttpClient( cache: Cache ) : HttpClient = HttpClient(cache) }
188. Metro IR Pipeline Scope — @SingleIn(AppScope : : class) IrBinding.Provided — Cache IrBinding.Provided — HttpClient @DependencyGraph interface AppGraph { val app: WeatherApp }
189. Metro IR Pipeline Scope — @SingleIn(AppScope : : class) IrBinding.Provided — Cache IrBinding.Provided — HttpClient Accessor — app: WeatherApp @DependencyGraph interface AppGraph
190. Metro IR Pipeline WeatherApp
191. Metro IR Pipeline WeatherApp class WeatherFormatter class WeatherService
192. Metro IR Pipeline WeatherApp class HttpClient class WeatherFormatter class Cache class WeatherService BindingLookup Cache: IrBinding.Provided HttpClient: IrBinding.Provided
193. Metro IR Pipeline WeatherApp class HttpClient class WeatherFormatter class Cache class WeatherService
194. Metro IR Pipeline WeatherApp (IrBinding.ConstructorInjected) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) Cache (IrBinding.Provided) HttpClient (IrBinding.Provided)
195. Metro IR Pipeline Tarjan's Algorithm WeatherApp (IrBinding.ConstructorInjected) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) Cache (IrBinding.Provided) HttpClient (IrBinding.Provided)
196. Metro IR Pipeline Tarjan's Algorithm njected) tructorInjected) ctorInjected)
197. Metro IR Pipeline Kahn's Topo Sor t WeatherApp (IrBinding.ConstructorInjected) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) Cache (IrBinding.Provided) HttpClient (IrBinding.Provided)
198. Metro IR Pipeline Kahn's Topo Sor t Cache (IrBinding.Provided) HttpClient (IrBinding.Provided) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected)
199. Metro IR Pipeline Cache (IrBinding.Provided) HttpClient (IrBinding.Provided) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected)
200. Metro IR Pipeline @DependencyGraph @SingleIn(AppScope : : class) interface AppGraph { val app: WeatherApp } Cache (IrBinding.Provided) HttpClient (IrBinding.Provided) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected)
201. Metro IR Pipeline class $$MetroGraph : AppGraph { }
202. Metro IR Pipeline class $$MetroGraph : AppGraph { } Cache (IrBinding.Provided) HttpClient (IrBinding.Provided) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected)
203. Metro IR Pipeline class $$MetroGraph : AppGraph { } ProviderFieldCollector Cache (IrBinding.Provided) HttpClient (IrBinding.Provided) WeatherFormatter (IrBinding.ConstructorInjected) WeatherService (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected)
204. Metro IR Pipeline class $$MetroGraph : AppGraph { } WeatherService ProviderFieldCollector
205. Metro IR Pipeline Cache (IrBinding.Provided) HttpClient (IrBinding.Provided) WeatherFormatter (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected) class $$MetroGraph : AppGraph { private val weatherServiceProvider: Provider<WeatherService> }
206. Metro IR Pipeline WeatherFormatter (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected) class $$MetroGraph : AppGraph { private val weatherServiceProvider: Provider<WeatherService> = DoubleCheck.provider(…) }
207. Metro IR Pipeline WeatherFormatter (IrBinding.ConstructorInjected) WeatherApp (IrBinding.ConstructorInjected) class $$MetroGraph : AppGraph { private val weatherServiceProvider: Provider<WeatherService> = DoubleCheck.provider( WeatherService.$$MetroFactory.create( $$HttpClientProvider.create( $$CacheProvider() ) ) ) }
208. Metro IR Pipeline class $$MetroGraph : AppGraph { private val weatherServiceProvider: Provider<WeatherService> = DoubleCheck.provider( WeatherService.$$MetroFactory.create( $$HttpClientProvider.create( $$CacheProvider() ) ) ) override val app: WeatherApp get() = WeatherApp$$MetroFactory.create( this.weatherServiceProvider, WeatherFormatter$$MetroFactory.create() ).invoke() }
209. Metro IR Pipeline class $$MetroGraph : AppGraph { private val weatherServiceProvider: Provider<WeatherService> = DoubleCheck.provider( WeatherService.$$MetroFactory.create( $$HttpClientProvider.create( $$CacheProvider() ) ) ) override val app: WeatherApp get() = WeatherApp$$MetroFactory.create( this.weatherServiceProvider, WeatherFormatter$$MetroFactory.create() ).invoke() }
210. ੉৻ী ׮ܲ Ѫٜ • ૐ࠙࠽٘-ౠ൤ য֢ప੉࣌ ҙ۲ ઱੄ • createGraph() ৬ createGraphFactory() ഐ୹ ߸ഋ val graph = createGraph<AppGraph>() val graph = AppGraph.$$MetroGraph()
211. What if validation fails?
212. What if validation fails?
213. What if validation fails?
214. What if validation fails?
215. Advanced Usage Binding containers @Includes Member injection Valid cycles Optional Top-level function injection Contribution replacements/excludes Compose integration Repor t s Circuit
216. Interop & Adoption https://zacsweers.github.io/metro/latest/adoption.html
217. Component Interop @Component interface StartupComponent { val httpClient: HttpClient / / . . . } @DependencyGraph interface AppGraph { @DependencyGraph.Factory interface Factory { fun create( @Includes startupComponent: StartupComponent ) : AppGraph } } https://zacsweers.github.io/metro/latest/adoption.html
218. Annotations Interop @Component interface StartupComponent { val httpClient: HttpClient } class HttpClient @Inject constructor( val cache: Provider<Cache> ) metro { interop { enableDagger() enableAnvil() } } https://zacsweers.github.io/metro/latest/adoption.html
219. Custom Code Generators https://zacsweers.github.io/metro/latest/adoption.html
220. Migration https://zacsweers.github.io/metro/latest/adoption.html
221. Metro Docs: https://zacsweers.github.io/metro/ API: https://zacsweers.github.io/metro/api/0.x/ Repo: https://github.com/zacsweers/metro Me: https://github.com/l2hyunwoo